Lighting and usability features for key structures and keypads on computing devices

ABSTRACT

A keypad is provided for a computing device. The keypad includes one or more lighting devices or mechanisms for illuminating a plurality of keys structures. In an embodiment, the plurality of key structures are formed from a milky material.

RELATED APPLICATION INFORMATION

This application is a continuation of U.S. patent application Ser. No.11/779,792, filed Jul. 18, 2007 entitled, “LIGHTING AND USABILITYFEATURES FOR KEY STRUCTURES AND KEYPADS ON COMPUTING DEVICES”; which isa continuation of the following applications:

U.S. patent application Ser. No. 11/203,809, filed Aug. 13, 2005, nowU.S. Pat. No. 7,275,836;

U.S. patent application Ser. No. 11/203,808, filed Aug. 13, 2005, nowU.S. Pat. No. 7,294,802; and

U.S. patent application Ser. No. 11/203,824, filed Aug. 13, 2005.

All of the aforementioned priority applications are hereby incorporatedby reference in their entirety.

TECHNICAL FIELD

Embodiments of the invention relate to key structures and keypads forcomputing devices. In particular, embodiments of the invention relate tolighting and usability features for key structures and keypads oncomputing devices.

BACKGROUND

Keypads are important aspects of computing devices. With regard to smallform-factor keypads in particular, the keypads tend to establish theoverall form-factor of a computing device. The keypad is often a veryvisible and highly used component of such computing devices.

Messaging devices, in particular, have need for QWERTY style keyboards.Such keyboards are often operated by the user using thumbs. Key size,visibility, and sensation are important characteristics forconsideration in the design of small form-factor keyboards. One furtherconsideration is usability of such features in darkened environment.Many users typically need to see some or all keys of a keyboard whenthumb typing on a small form factor keyboard, as such devices haveclosely spaced keys that may require visual coordination.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is an exploded side view of an illuminated keypad for use with acomputing device, under an embodiment of the invention.

FIG. 1B illustrates a keypad of FIG. 1A in an assembled position, underan embodiment of the invention.

FIG. 1C is a close-up side view of a section of a keyboard shown byFIGS. 1A and 1B, according to an embodiment of the invention.

FIG. 2A is an exploded side view of an illuminated keypad for use with acomputing device, under another embodiment of the invention.

FIG. 2B illustrates a keypad of FIG. 2A in an assembled position, underanother embodiment of the invention.

FIG. 2C is a close-up side view of a section of a keyboard shown byFIGS. 2A and 2B, according to another embodiment of the invention.

FIG. 3A and FIG. 3B illustrate different key structure designs, under anembodiment of the invention.

FIG. 4A to FIG. 4D illustrate use of polarization material to distributediscrete light sources underlying a keypad of a computing device, underan embodiment of the invention.

FIG. 5 illustrates an embodiment of the invention in which a lightinglayer is configured to include a combination of panel lighting anddiscrete lighting.

FIG. 6A, FIG. 6B, and FIG. 6C illustrate key structure designs forfacilitating illumination, under an embodiment of the invention.

FIG. 7 illustrates a keypad with slits to facilitate key structuremovement and minimize light leakage, under an embodiment of theinvention.

FIG. 8A-8C illustrate use of a dampening layer inside a keypad stack,under an embodiment of the invention.

DETAILED DESCRIPTION

Numerous embodiments are described in this application for enhancinglighting and usability of key structures and keypads of computingdevices. It is contemplated that the various features described by thisapplication may be combined in any one of numerous ways.

According to an embodiment, a key structure is provided for a computingdevice. The key structure is formed from a milky material.

In another embodiment, a keypad is provided for a computing device. Thekeypad includes one or more lighting devices or mechanisms forilluminating a plurality of keys structures. In an embodiment, theplurality of key structures are formed from a milky material.

One or more embodiments described herein provide a keypad for acomputing device. In an embodiment, a plurality of key structurescomprise the keypad, and each of the key structures may be referenced bya top end that includes a surface for receiving user-contact and abottom end that is opposite to the top end. A plurality of discretelight sources may be provided underneath the plurality of keystructures, so that the plurality of light sources illuminates each ofthe key structures from the bottom end. A material provided between thetop of each key structure in the plurality of key structures and theplurality of discrete light sources to cause light generated by theplurality of light sources to be transmissive through each keystructure.

A keypad is any multi-key assembly. A keyboard is an implementation of akeypad.

As used herein, something is “milky” if it is with creamy body colorthat dominates the diffracted color. In one embodiment, a resin, keystructure or other item is milky if it contains white colored resin,meaning resin having at least some visibly detectable white or off-whitematerial. A material is white if the material contains all the colors ofthe spectrum.

Diffusion of Bright Light Underlying a Keypad

One or more embodiments described herein provide mechanisms fordiffusing bright light provided within a housing of a computing devicefor purpose of illuminating the device's keypad or keyboard. Inparticular, some light sources, such as provided by white Light EmittingDiodes (LEDs) emit light that is bright and discrete. The brightness ofsuch lights make their use desirable. But, absent some interveningdesign for handling the discreteness and brightness of the emittedlight, the use of such light sources can result in a keypad beingunevenly lit from underneath. In such cases, shadows or cold spots mayform on regions that are further away from light sources, while brightor hot spots form on region closes to light sources. Furthermore,factors other than the positioning of light sources may result in theformation of hot and cold spots from the use of discrete light sources120. Examples of such other key structure features include shading,colorization, use of different materials or surface materials to formsome key structures and not others, and different ornamentationsprovided on key structures on the keypad.

One or more embodiments described herein include keypad designimplementations and mechanisms for diffusing and distributing lightemitted from LEDs and other bright and discrete light sources. FIG.1A-1C, FIG. 2A-2C, and FIGS. 3A and 3B illustrate alternativeimplementations in which diffusive material is used to diffuse emittedlight from discrete light sources of a keypad for use with a computingdevice.

FIG. 1A is an exploded side view of an illuminated stack 102 of a keypad100 for use with a computing device, under an embodiment of theinvention. FIG. 1B illustrates the keypad in an assembled position. Anexample of a computing device on which the keyboard stack 102 may beimplemented is a handheld computing device, such as a personal digitalassistant, mobile manager device, or cellular/pocket phone. A specificexample of a computing device for use with an embodiment of theinvention is a multi-functional cellular device, sometimes called a“smartphone” (e.g. TREO 650 manufactured by PALM, INC.). In suchimplementations, the keypad 100 has a small form-factor suitable for usewith thumb or finger typing.

As shown by FIGS. 1A and 1B, keypad 100 includes a plurality of keystructures 110 that overlay a substrate 120 on which a plurality oflight sources 122 are provided. The substrate 120 may include electricalcontact elements 130 that are actuatable through use of thecorresponding key structures 110. A carrier 112 may interconnect theplurality of key structures 110. In one implementation, the carrier 112and the plurality of key structures 110 form a monolithic component. Inanother implementation, the carrier 112 and the plurality of keystructures 110 may be separately formed elements.

In an embodiment, each key structures 110 includes an actuation member115 that extends from its bottom end 116. In one implementation, theactuation members 115 are unitarily or integrally formed with thecorresponding key structures 110. In another implementation, carrier 112and key structures 110 are separately formed and combined, and actuationmembers 115 are unitarily or integrally formed from the carrier 112. Instill another embodiment, the actuation members 115 have their ownseparate carrier and are separately formed from the key structures 110.

Each actuation member 115 may travel inward with compression orinsertion of the corresponding key structure 110 to actuate acorresponding one of the electrical contact elements 130. Actuation ofanyone of the electrical contact elements 130 triggers a signal that isreceived and processed by a processor 150 of the computing device. Thesignal generated from the triggering of any particular key is recognizedby the processor 150 as having a value (e.g. alphabet or number value).The electrical contact elements 130 may be provided on a printed circuitboard 132, or electrically interconnected substrate (e.g. flex circuitand substrate). In one implementation, the light sources 122 may beprovided on a separate sheet 124 that overlays the printed circuit board132.

In an embodiment, light sources 122 are LEDs, although other types oflight sources can be used. The LEDs provide a benefit of providingbright light for their relative size. In a configuration shown by FIG.1A-1C, the LEDs are disposed evenly between adjacent key structures 110that form the column or subset of the overall keypad. However, inpractice, the distribution of LEDs or other discrete light sources maynot be even. For example, in one implementation, 14 LEDs are used toilluminate 40 key structures. In such implementations, some keystructures 110 may overlay or be more proximate to individual lightsources 122 than other key structures. Regardless of whether LEDs areevenly or unevenly distributed, an illumination of a keyboard formedfrom the plurality of key structures 110 may carry uneven lighting. Forexample, some keys may be more lit than others, while individual keystructures may have one region that is darker than another.

Accordingly, stack 102 includes components or elements to diffuse ordistribute light emitted from light sources 122. The light sources 120may illuminate individual key structures 110 from their respectivebottom end 116. The result is that illumination is provided from a topend 118 of each respective key structure 120. The top end 118 of eachindividual key structure 110 may be the surface that receives usercontact. The top end 118 of each key structure 110 may also displaymarkings, shading, colorization, and/or printed matter. As such, the topend 118 of each key structure 110 corresponds to the surface from whichthe desired illumination effect is to take place.

In an embodiment, diffusive or light-distributive material is providedwith or between the key structures 110 and the light sources 122. Suchmaterial may enable individual key structures 110 to be illuminatedwhile at the same time diffusing light emitted from the individual lightsources. One result achieved is that a keypad (or desired regionsthereof) is illuminated substantially uniformly through diffusion oflight from the discrete and bright light sources 122. Such a uniformlylit keypad may be well lit from underneath, without distracting hot orcold spots in the lighting. Accordingly, an embodiment provides thatindividual key structures 110 of a keypad have the followingcharacteristics: (i) partially transmissive to light so that lightentering the bottom end 116 of the key structures is partially carriedthrough that structure; (ii) diffusive or distributive of light, so thatsome light used to illuminate each key structure 110 is diffused withinand/or underneath the key structure 110.

In an embodiment shown by FIG. 1A-1C, individual key structures arecomprised of diffusive material to effect light from light sources 122.Embodiments described herein use milky material to diffuse light thatcomes in contact with or enters each key structure. Milky materialenables light to be diffused while at the same time enabling the lightto be transmissive. FIG. 1B illustrates the keypad 100 with keystructures 110 formed of milky material or resin overlaying lightsources 122 in an operative position. The material of the key structures110 diffuse and distribute the light emitted from the light sources 122.

FIG. 1C is a close-up side view of a set of key structures 110 shown inFIGS. 1A and 1B. A body 105 of each key structure may be formed frommilky resin. Numerous alternatives to resin may be used, including forexample, liquid, foam, or other matrix material. The carrier 112 extendsunderneath the key structures 110. Actuation members 115 extend from thebottom end 136 of each key structure 110 and can travel inward throughdeflection or movement of the corresponding key structure in order toactuate the electrical contact 130. In an embodiment shown, theelectrical contacts are domes that are actuated when correspondingactuation members 115 travel inward and deflect the domes inward. Byproviding the body 105 of the key structures 110 as being formed fromthe milky resin, one embodiment provides that no other layer or materialis needed to effectuate diffusion or distribution of light emitted fromsources 122.

FIG. 2A-2C illustrate an alternative embodiment in which individual keystructures 210 of a keypad 200 are formed from light-transmissivematerial, but a layer 208 of milky material is disposed between thebottom ends 216 of the key structures 210 and the light sources 222. InFIG. 2A, an exploded view of a stack 202 of the keypad 200 is shown withthe key structures 210 overlaid over corresponding contact elements 230.

In FIG. 2B, the stack 202 is shown in the assembled configuration withthe layer 208 disposed within the stack 202. The milky layer 208 may bedisposed just over the layer carrying the light sources 222. In oneimplementation, the light sources 222 may be carried on a separate layer224, and the actuation members 215 may translate into the milky layer208 in order to electrically actuate a corresponding contact element 230on a printed circuit board 232.

One embodiment provides for milky layer 208 to be formed of a thinsilicon rubber material. The layer 208 may provide a cushion ordampening effect for the actuation members 215 translating into thecorresponding contact elements 230, while at the same time forming adiffusion layer for light emitted from light sources 222.

As shown by FIG. 2C, a body 205 of the individual key structures 210 maybe non-milky (e.g. clear or translucent). While the body 205 may benon-milky, surface ornamentations, paint, ink or printed material may beprovided on a top surface 218 so as to be illuminated by the light fromthe light sources 222.

FIGS. 3A and 3B is a side view of an alternative key structure design inwhich a milky layer is thinly disposed, under an embodiment of theinvention. In an embodiment of FIG. 3A, a top surface 318 of a keystructure 310 is provided a paint layer 322. The paint layer 322 mayinclude, at least partially, a milky color. Additional surfaceornamentations may be provided on the key structure in a manner thatcreates a desired illuminative effect. FIG. 3B illustrates a painted orformed layer underneath the carrier 208 (FIG. 2C) that adjoinsindividual key structures 310. Other embodiments may provide a milkypaint on a top surface (facing upward) of the carrier 312 with ink orother decorative material provided on either the top surface 318 orunderneath the structure at a thickness of or near the carrier 208 (FIG.2C).

Light Distribution

As an alternative or addition to diffusing light emitted from lightsources underlying a keypad, one or more embodiments of the inventioncontemplate distributing light from light sources. A difference betweendiffusion of light and distribution of light sources is that light froma source is diffused when it is made less discrete and more spread out,while light from a discrete source is maintained relatively discrete butdistributed to more places in discrete form. FIG. 4A-4D illustrate useof polarization material to distribute discrete light sources underlyinga keypad of a computing device. One result achieved by the embodimentsshown is that light is distributed more evenly underneath a keyboard.

In FIG. 4A, a single light source 420 is shown prior to application of apolarization material. In FIG. 4B, the light source 420 is overlaid by afirst polarization material 430. The first polarization material 430serves to create an apparent light 422 source adjacent to the originallight source 420. The apparent light source 422 is not a real lightsource, but a filtered reflection created by the application of thefirst polarization material 430. The orientation of the firstpolarization material 430 uses a filter that creates the apparent lightsource 422 in a particular direction with respect to the original lightsource 420.

In FIG. 4C, the light source 420 and the first polarization material 430are applied a second polarization material 440. The second polarizationmaterial 440 overlays the first polarization material 430. In oneembodiment, the second polarization material 440 uses a filter thatcreates a second set of apparent light sources 450, 452 in a directionthat is orthogonal to the direction that first polarization materialcreates the apparent light source 422. For example, the firstpolarization material 430 may use a horizontal filter that distributesthe original light source 420 in one of the horizontal directions. Thesecond polarization material 440 may use a vertical filter thatdistributes the original light source 420 and the apparent light source422 created by the first polarization material vertically.

In FIG. 4C, one of the second set of apparent light sources 440 isreflected off the original light source 420, while the other apparentlight source 452 is reflected off the apparent light source 422 createdby the first polarization layer. In the example shown, application ofthe first polarization material 430 and the second polarization material440 quadruples the original light source 420, in that the original lightsource is provided three apparent light sources 422, 450, and 452.

FIG. 4D illustrates disposition of the first polarization material 430and the second polarization material 440 in a stack 402 of a keypad 400.In an embodiment shown, the first polarization material 430 and thesecond polarization material 440 are positioned within the stack 402between the light sources 422 and an underside of the individual keystructures 410.

In order for any polarization material to be effective, animplementation provides that each polarization material is provided agap distance 456 from a light source (actual or apparent) that is to bedistributed. For example, in one implementation, the suitable gapdistance 456 is on the order of millimeters. When two or morepolarization materials are used in the stack 402, each material may needto have a thickness separation (e.g. 2-4 millimeters).

With regard to embodiments described in FIG. 4A-4C, the degree of shiftbetween the apparent and actual light sources may vary. For example,polarization materials may be used to provide a slight shift so that theapparent and actual light sources overlap substantially or slightly.

Additionally, three or more layers of polarization materials may beused, depending on design implementation. It should be noted that whileuse of polarization material described with FIG. 4A-4D provides forreflecting actual and apparent light sources as discrete sources, otherembodiments may provide for using polarization material that diffusesand shifts and distributes light from one actual or apparent lightsource to another region.

Combination Lighting Layer

As described above, discrete light sources such as LEDs provide thebenefit of brightness, which in turn provide better visibility andaesthetics of a key structure to a user. However, as also described,discrete light sources also provide shading, or hot/cold spots, unlessthe light emitted from such sources is treated in some manner. Analternative to LEDs and other forms of discrete light sources is a lightsource that emits light uniformly and evenly across a region thatencompasses an entire keypad, or at least portions of the keypad onwhich lighting is desired. This type of lighting may be referred to as alighting panel. A specific example of this kind of light source is anelectroluminescent (EL) panel. While panel lighting has the benefit ofproviding uniform and distributed lighting, such lighting does nottypically provide the same brightness as LEDs, at least not unless theamperage and size of the panel lighting is increased to be significantlygreater than what would be required if only LEDs were to be employed.

Embodiments of the invention contemplate that a given keypad or keyboarddesign has some key structures that need bright lighting and other keystructures that are adequately lit with panel lighting. Accordingly,FIG. 5 illustrates an embodiment of the invention in which a lightinglayer is configured to include a combination of panel lighting anddiscrete lighting. In particular, FIG. 5 illustrates a keypad assemblycomprising a key structure layer 510, a lighting layer 520 and aelectrical contact layer 530. For purpose of simplicity, an embodimentshown by FIG. 5 is assumed to implement the plurality of key structures510 as a monolithic structure. A carrier 512 or web may interconnect thekey structures 514 of the key structure layer 510, although otherimplementations may provide for some or all of the key structures to beseparated or in strips. Actuation members (not shown) may extend from abottom surface (not shown) of each key structure 514 for purpose ofenabling contact elements distributed over a substrate to be actuatablewith insertion of the corresponding key structures. Additional materialsmay be added to the assembly, including materials for effectingusability of key structures and/or actuation members.

The key structures 514 may be arranged to provide one or more coloredkeys, keys with surface ornamentations and darkened appearances, andkeys formed from different types of material. For example, in a smallform-factor QWERTY keyboard, one embodiment provides for a shaded orcolorized set of key structures 514, designated by a region 515, forpurpose of indicating keys that have both numeric and alphabet values.Another implementation provides for the keypad to include specializedkeys 518 that are colored are formed from more opaque material, such asapplication keys (for quick launching applications) or navigation keys(set for navigation by default).

In one embodiment, lighting layer 529 may include white LEDs that formdiscrete light sources distributed on a substrate 525 containing an ELpanel 526. The LEDs are positioned strategically to conserve energywhile lighting key structures that require the most light. In theexample shown, the key structures that require the most light are theapplication keys 518, as they are colorized (e.g. red, green, and blue).As such, FIG. 5 provides LEDs 522 in alignment to backlight theapplication buttons 518. However, another embodiment may provide forusing LEDs 522 to illuminate key structures in region 515. Other keystructures 520 that are not colorized or otherwise darkened may beilluminated by the EL panel 526. In one embodiment, key structuresilluminated by either light source may include milky material or layers,or have features of other embodiments described in this application. Thesubstrate 525 holding the EL panel 526 may be a flex circuit (see FIG.5B), which in turn is connected to the electrical contact layer 530. Inone embodiment, EL panel 526 is tacked on to the flex circuit 525 topreserve electrical connectivity. Individual LEDs 522 are soldered ontothe flex circuit 525. Elements of the electrical contact layer 530 mayinclude individual snap dome contact switches 532 that actuate whencollapsed by actuation members such as described elsewhere in thisapplication.

Key Structure/Actuation Member Shaping

As shown, actuation members are elongated elements that travel inresponse to deflection or inward movement of corresponding keystructures. The actuation members are used to convert key presses intoswitching events for electrical switches that underlie key structures.Typically, actuation members are cylindrical or even rectangular andextend downward from a bottom surface of a key structure.

In the context of lighting, the edged nature of actuation members arenot conducive. The edges of actuation members reflect or divert lightfrom the light sources, while better illumination results would resultif such light was absorbed into the key structures and illuminated.

FIG. 6A is an enlarged view of a key structure 610 having a unitarilyformed actuation member 620 that is shaped to receive and betransmissive to light, under an embodiment of the invention. The keystructure 610 may include a key body 605 on which an exterior surface622 is formed. The exterior surface 622 may be the surface from which anillumination effect is desired. Both the actuation member 620 and thekey body 605 may be formed from translucent or milky material, so as tobe able to receive light and to at least be partially transmissive tolight. In an implementation, discrete light sources 630 may bepositioned adjacent to the actuation member 620. The actuation member620 may align over a contact element 640 provided on a substrate 644.The actuation member 620 includes a bottom surface 618 that is separateda distance h from the substrate. While FIG. 6A illustrates a separationdistance h is about or less than a height of the light sources, thevertical position of the light sources on the substrate may vary. Forexample, the light sources may be embedded or flush with substrate 644.

According to an embodiment, a shape of actuation member 620 is conical,with exterior surface of the actuation member extending to or near theboundary of the key body 605. In the example provided, the key body issymmetrical and round, creating the cone shape. In otherimplementations, the key body 605 may be non-round (e.g. square orrectangular) or irregular in shape (trapezoidal). In such alternativeimplementations, the exterior surface of the actuation member 620 mayconform to the shape or irregularity of the key body. For example, asquare key body may result in a pyramid shaped actuation member 620,while an irregular shaped key body 605 may result in an uneven conicalor tapered actuation member 620.

In FIG. 6A, the angled surface 621 forming the tapered section 625 issubstantially linear and edged when joining the bottom end. FIG. 6Cillustrates an alternative in which an angled surface 641 forming atapered section 645 is rounded into the bottom end 618. Embodiments suchas shown by FIG. 6A-6C illustrate actuation members that are shaped tobetter receive light from discrete light sources that are typicallyplaced adjacent to the actuation members, rather than directlyunderneath. Embodiments such as shown by FIG. 6A illustrate thattapering the actuation member in whole (or at least in part) isconducive to reducing reflection from LEDs and other light sources thatmay disposed adjacent and below the actuation members.

FIG. 6B illustrates an alternative key structure 670 in which one ormore open regions 650 are formed into the key body 665. The key body 665may correspond to the portion of the key structure 670 that is providedover a line C-C (corresponding to the housing line on a computingdevice). In one embodiment, resin or matrix material (including possiblymilky material) is removed from the key structure to form the openregions 650. The formation of open regions 650 means that more lightfrom light sources 668 may enter the boundary of the key structure 670.An actuation member 680 may extend from the key body 605 to form theshape shown. One implementation provides that the actuation member 680may be curved or irregular to accommodate the openings 650. The resultis brighter and better illuminative effect on exterior surface 612 ofthe key structure 670, as there is less thickness for light to passthrough in illuminating the key structure.

Embodiments shown with FIG. 6A-6B may incorporate key structure designsdescribed with other embodiments and implementations in any combination.For example, with regard to the key structure 670 shown in FIG. 6B, aninterior of the key structure 665 may be formed from milky resin orother matrix material. Alternatively, a paint layer may be providedsomewhere on or within the key structure to diffuse light that entersthe key structure. Furthermore, while the key structure may included theopen regions 650, the actuation member 680 may be tapered, or include atapered section, rounded or un-rounded, and otherwise be shaped toreceive light rather than reflect light.

Carrier Slits

To enhance the usability of a keyboard, it is desirable to lessen therestriction of movement of individual key structures when suchstructures are deflected and/or pushed inward by the user. FIG. 7 is atop view of a key structure layer, such as may be provided by any of theembodiments described above. The key structure layer 710 may include aplurality of key structures 715, provided in a QWERTY arrangement. Acarrier 712 may provide a web that joins the structures. The carrier 712may carry tension from the number of key structures 715 carried on it.The tension may provide unwanted resistance and guidance to the userwhen deflecting or pushing key structures inward. To lessen the tension,a slit pattern 735 may be formed on the carrier 712.

In FIG. 7, the position of a single light source 722 is shown underneaththe carrier 712. The light source 722 may be provided between four keystructures 715. One problem that may arise in forming slits into thecarrier 712 is that the presence of the light source may cause lightleakage through those slits. Light leakage is distracting andunaesthetic, thus preferably avoided. Accordingly, one embodiment shapesand forms light slits 735 on the carrier 712 to minimize the lightleakage. This requires consideration of the position of the light source722. One implementation provides that slits are provided about each keystroke in “L” or adjoining linear segments to form corners aboutindividual key structures, where the corners are distal to the lightsource for that key stroke. When adjoining key structures areconsidered, the resulting shape may correspond to an upside down “T”.Thus, for example, the key structures 715 labeled as “A” and “B” areprovide corner slits 735 which serve to hinge each of those keystructures on carrier 712 the non-slit side of the respective keystructures. However, with respect to the light source 722, the positionof the slits 735 is sufficiently distal to avoid light leakage. Thus,slits 735 are formed adjacent to a corner of a key structure most distalto an underlying light source. As such, the pattern of the light sources720 underlying the key structure layer 710 may be determinative of theslit pattern and its position.

It should be noted that darkened and/or colored keys fair worst withlight leakage. Light emitting from dark keys is more distracting to auser. Many factors, including key shape and distance to the proximatelight sources, need to be considered in forming slits around on darkenedkeys of a keyboard.

Alternative embodiments may use strips or sections to form the keystructure layer of a keyboard stack. Sectioning an otherwise monolithickeyboard into segments reduces the amount of tension that surroundsindividual keys as a result of the weight and presence of other keystructures formed on a common carrier. For example, in a QWERTYkeyboard, each row of key structures may be provided on a separatestrip, and the stripped sections may be combined in assembly to form thekeyboard. Alternatively, multiple key structures may be formed on “L” or“C” shaped sections, which are then intertwined at assembly to form themonolithic keyboard. While sectioning keyboards for assembly can reducetension on the carrier and thus enhance usability, the gaps caused bythe sectioning also produce light leakage. As such, a balance betweenthe number of sections and the amount of tolerable light leakage may bestruck, based on the particular implementation.

Dampening Layer

One or more embodiments may implement a dampening layer in connectionwith use of actuation members traveling into contact members.Embodiments described in this section may be implemented independentlyof other embodiments provided with this application. For example, adampening layer, such as described with FIG. 8A-8C, may be used with akeyboard that includes no lighting element. Alternatively, however, akeyboard stack having features described in this section may alsoimplement lighting features of other embodiments described elsewhere inthis application.

FIG. 8A illustrates a keyboard stack assembled to include a dampeninglayer, under an embodiment of the invention. The keyboard stack 802 mayinclude a plurality of key structures layer 810 with actuation members820 extending downward from individual key structures 812. The dampeninglayer 850 may correspond to a layer of deformable or flexible material.According to an embodiment, a dampening layer 850 may be overlaid on topof electrical contacts 830 distributed over a substrate 840 having aplurality of electrical contacts 830 that are actuatable by actuationmembers 820. One effect achieved by the dampening layer 850 is that itcushions and protects the electrical contacts 830 from jarring forces tothe housing of the computing device, or from forceful movements of theactuation members use and shock of the housing that contains thekeyboard assembly 800.

In an embodiment, the dampening layer 850 is provided over theelectrical contacts 830 (FIG. 8C) of the substrate 840. In animplementation in which lighting is provided, one embodiment providesfor discrete light sources, such as LEDs, to be provided on thesubstrate 840 and overlaid by the dampening layer 850. As described withFIG. 2A-2C, the dampening layer 850 may be milky, or alternativelytranslucent, to enable the light sources 845 to backlight the keystructures 812.

An overall thickness t of the dampening layer may be thin, of the orderof less than one millimeter. In one embodiment, the thickness t of thedampening layer is less than 0.5 millimeter. In one specificimplementation, the thickness t of the dampening layer is about (within90%) of 0.25 millimeters. As mentioned, a suitable material for thedampening layer is silicon rubber. In such an implementation, thelighting sources 845 may correspond to light pipes or white LEDs.

FIG. 8B illustrates a key structure 812 without use of the dampeninglayer. In such a design, the actuation member has length L. FIG. 8Cshows a comparison of the dampening layer 850 overlaid onto theelectrical contact 830. To accommodate the extra thickness of thedampening layer 850, one embodiment provides for the actuation member820 to be reduced in length L by the thickness t of the dampening layer.Insertion or deflection of key structure 812 causes actuation member 820to travel and actuate the contact element 830. In one embodiment, theelectrical contact element 830 is a snap dome, and the dampening layer850 dampens the impact of the actuation member 820 (which may be formedfrom hard plastic) with the electrical contact element 830. Among otheradded benefits, the dampening layer 850 may reduce the noise and tactileresponse of the snap dome contact element, thus eliminating or reducing“clicking”. Furthermore, when the computing device is dropped, the snapdome contact element is less likely to be pierced or made dysfunctionalby the rigid actuation member.

Although illustrative embodiments of the invention have been describedin detail herein with reference to the accompanying drawings, it is tobe understood that the invention is not limited to those preciseembodiments. As such, many modifications and variations will be apparentto practitioners skilled in this art. Accordingly, it is intended thatthe scope of the invention be defined by the following claims and theirequivalents. Furthermore, it is contemplated that a particular featuredescribed either individually or as part of an embodiment can becombined with other individually described features, or parts of otherembodiments, even if the other features and embodiments make nomentioned of the particular feature. This, the absence of describingcombinations should not preclude the inventor from claiming rights tosuch combinations.

1. A keypad for a computing device, the keypad comprising: a pluralityof key structures, each of the plurality of key structures beingreferenced by a top end that includes a surface for receivinguser-contact and a bottom end opposite to the top end; a plurality ofdiscrete light sources provided underneath the plurality of keystructures, the plurality of light sources illuminating each of the keystructures from the bottom end; a milky material provided between thetop of each key structure in the plurality of key structures and theplurality of discrete light sources to cause light generated by theplurality of light sources to be transmissive through each keystructure.
 2. The keypad of claim 1, wherein the milky material isprovided within each of the plurality of key structures.
 3. The keypadof claim 1, wherein the milky material is a resin that forms each of theplurality of key structures.
 4. The keypad of claim 1, wherein the resinis substantially white.
 5. The keypad of claim 1, wherein the milkymaterial is provided as a separately formed layer between the pluralityof key structures and the plurality of light sources.
 6. The keypad ofclaim 1, wherein the plurality of discrete light sources correspond to aplurality of light emitting diodes.
 7. The keypad of claim 1, furthercomprising a carrier layer that interconnects the plurality of keystructures from the bottom.
 8. The key structure of claim 1, wherein thekey structure includes a surface film that forms an exterior of the keystructure, and wherein the milky resin forms an interior of the keystructure.